Prognostic Value of Brain Metastasis-Free Interval in Patients with Breast Cancer Brain Metastases.

Background: In patients with breast cancer brain metastases (BCBM), time between primary tumor diagnosis and appearance of brain metastases varies widely. Despite being a readily available clinical parameter, it remains unclear whether brain metastasis-free interval (BMFI) carries prognostic value among breast cancer patients. The aim of this study was to compare characteristics and overall survival among patients with varying BMFIs and to assess the prognostic role, if any, for BMFI.

Methods: We retrospectively reviewed 3 institutional databases of adult female patients who were treated for BCBM between 1996 and 2017. Cox proportional hazards model and Kaplan-Meier survival curves were used to determine prognostic value of BMFI for survival.

Results: A total of 503 patients were included. Median age at first brain metastasis was 52 (interquartile range [IQR]: 45-58) years. Median BMFI was 38 months (IQR: 18-66), and median overall survival was 17 months (IQR: 8-31). In univariate Cox proportional hazards model, younger age at BCBM, estrogen receptor (ER)+/human epidermal growth factor receptor 2 (HER2)+ tumor subtype, and the absence of liver or lung metastases were associated with longer survival. BMFI >3 years was not associated with longer survival (hazard ratio [HR] = 1.13; P = 0.21). In multivariate analysis, only subtype (ER+/HER2+ vs. ER-/HER2-; HR = 0.77; P = 0.02) and liver metastases (HR = 1.36; P = 0.01) were prognostic for survival. There was no significant association between BMFI and overall survival (HR = 0.99; P = 0.91).

Conclusions: In this large, retrospective cohort of breast cancer patients, BMFI was not prognostic for overall survival.